The spine can be considered to be a series of movable segments made up of vertebrae and discs. Due to trauma, disease, and/or aging, the spine may be subject to degeneration. This degeneration may destabilize the spine and cause pain and/or nerve damage. Medical procedures are often required to either ease back pain, repair damage, or to prevent future damage.
One procedure that is often used to treat back pain or spinal damage is spinal fusion. Spinal fusion is a surgical technique used to combine two or more adjacent vertebrae. Supplemental bone tissue is used in conjunction with the patient's natural osteoblastic processes in a spinal fusion procedure. Spinal fusion is used primarily to eliminate back pain caused by the motion of the damaged vertebrae by immobilizing adjacent vertebrae. Conditions for which spinal fusion might be done include degenerative disc disease, treatment of a spinal tumor, a vertebral fracture, scoliosis, degeneration of the disc, spondylolisthesis, or any other condition that causes instability of the spine.
One problem with prior art spinal fusion techniques relates to device migration. For example, prior to complete bone fusion, a spinal fusion device may migrate from the desired position. In examples where bone screws are used, the insertion and tightening of the bone screws tends to cause device migration. Another problem with typical prior art spinal fusion techniques is that fusion devices, or associated plates or fasteners, protrude excessively from the spine, causing discomfort, damage, or danger to surrounding vascular or neurological tissues.
Another problem with prior art spinal fusion techniques relates to preparing the end plates of the vertebrae for fusion. Typically, a surgeon will scrape the end plates with surgical instruments (e.g., burrs, gouges, curettes, etc.), while holding adjacent end plates apart with another instrument. This procedure can be difficult and not exact. In addition, there is a danger of damaging nearby tissue while scraping the end plates.
Yet another problem with prior art spinal fusion techniques relates to the surgical approach, anatomic restrictions of the patient as a result of the surgical approach, instrumentation used to perform the fusion surgery, and the size and shape of the fusion device itself. In combination, these factors can result in large surgical wounds, massive disruption of, and danger to surrounding tissues during placement of the fusion device.
There is therefore a need for spinal fusion devices and instruments, as well as related spinal fusion procedures, that adequately treats degenerative disc disease and other spinal conditions, while providing improvements over the prior art.